Avengers: Endgame snapped box office records in half, with $357M US box office opening and more than $1.2B worldwide.

The galaxy-size haul is thanks to a decade of storytelling with beloved characters, with big credit to social media, said writer Joe Russo, interviewed at the Milken Institute Global Conference on May 29 in Beverly Hills.

Joe said that social media, film eventizing, and serial storytelling contributed to Avengers Endgame success.

Social Media

“I think that Marvel, the MCU had a unique rise along side social media,” Joe said in an interview with CNN’s Julie Boosting. “I don’t think that we could have got to these kinds of numbers without a significant conversation on social media. It’s just a global community having a conversation about a story. And then that drives a desire to see it, a sense of FOMO. Everybody needs to get to the theaters as soon as possible. I just don’t think we could achieved this kind of success without it.”

The Russos themselves have been active on social media with their 2M followers on Instagram and 750K on Twitter. They’ve been tweeting everything from set pics, to reminders #DontSpoilTheEndgame to thanks to fans.

Social Media buzz has been brewing and bursting across platforms. Facebook Groups for those who’ve seen Endgame, like “Endgame Release Therapy” sprouted up so those who saw the movie could talk about it without spoiling it for friends. Reddit conversations have blossomed with analysis of the film. On Instagram, the hashtag #AvengersEndgame which had about 250,000 tags a month ago, has skyrocketed to more than 2M mentions.

On Twitter, #AvengersEndgame was trending all opening weekend. Twitter launched more than 30 #AvengersEndgame hashtag emojis for the characters from #CaptainAmerica and #IronMan to #Korg #Miek and #KevinFeige

Film Eventizing

Creating an event-film helps. People flocked to theaters to see it for the story. And they flocked opening weekend to see it as soon as possible, not just to be able to talk about it with friends, but so it wouldn’t be spoiled for them on social media. Hollywood studios still want huge audiences on opening weekend, and FOBS Fear of Being Spoiled has a multiplier effect along with FOMO Fear of Missing Out.

“Eventizing is critical for theatrical success right now,” Joe said. “Creating that conversation on social media is critical.

Stopping Thanos has become a pop culture event.

Serialized Storytelling

“Serialized storytelling is really becoming the future of narrative,” Joe said. “It drives conversation between each segment of the story.

In fact, Disney’s upcoming streaming service Disney+ will continue serialized storytelling with Avengers characters when it debuts this fall. In WandaVision, Elizabeth Olson and Paul Bettany reprise their roles. The Loki series stars Tom Hiddleston. Falcon and Winter Soldier stars Anthony Mackie and Sebastian Stan. It’s unclear exactly how these stories will relate to the concluding events of Endgame, but that anticipation itself will driver viewers to seek more serialized stories.

In addition to these explanations for the film’s strong opening weekend, other factors included online sales reports and promotions.

Online Promotions

Fortnite announced Avengers Endgame themed skins on April 25, same day as the film’s release. Fornite players could pay for and unlock Avengers costume skins, and weapons including Captain America’s shield, Iron Man’s repulsers, Thor’s new hammer, and Hawkey’s bow. This is highly unusual as Disney and Marvel is usually very strict about having only its characters be pictured with their character-appropriate weapons. SPOILER: Fortnite is even featured in the film, for additional in-movie tie-in. How much did Epic Games pay for the promo?

Google joined the fun on opening weekend. Fans who Googled “Thanos” on opening weekend and clicked on the Infinity Gauntlet icon saw it do a Snap animation, with a fun screen-dissolving animation that could make you smile – or cry.

Online Sales

Fandango reported that advance ticket sales surpassed the current record holder: Star Wars: The Force Awakens, which is the #1 grossing film ever. This high demand may have encouraged others to get tickets opening weekend.